Means for dishing metal blanks for drawing



March 13, 1962 G. A. LYON 3,024,832

MEANS FOR DISHING METAL BLANKS FOR DRAWING Original Filed April 26, 1955 Ezra TJZUT George Ajberf Lyon b 4; al y/ il United States Patent f 3,024,832 MEANS FOR DISHI NG METAL BLANKS FOR DRAWING George Albert Lyon, Detroit, Mich, assi nor to Lyon Incorporated, Detroit, Mich, a corporation of Delaware Original application Apr. 26, 1955, Ser. No. 504,015. Divided and this application Aug. 8, 1958, Ser. No. 754,094

2 Claims. (Cl. 153-2) The present invention relates to improvements in dishing metal blanks for drawing and more particularly concerns the cold working of steel blanks derived from rolled or otherwise formed slab, especially suitable for producing efiiciently and economically large bomb head shells or the like.

The present application is a division of my application Serial No. 504,015 filed April 26, 1955.

Large size shells have usually been made by utilizing fiat plate bent into cylindrical form and seamed along the meeting edges of the blank by welding, or drawn tubular stock has been used in suitable length cut from longer stock lengths of tubing. Such prior methods have had numerous disadvantages such as lack of structural or grain uniformity in the tubular blank, great difiiculty in attaining or maintaining symmetry, especially in the finished shell, and inevitably high production costs.

A warhead shell for a low drag bomb of the 500 lb. size may be from 60 to 65 inches in length and to inches in outside diameter. Larger sizes of bomb. of course, require proportionately larger size Warhead shells. Shells of this size require substantial mass of material in their production and proper distribution of the material for adequate strength where required in the shell structure, with nevertheless minimum mass consistent with strength to afford as light weight as possible in order to reduce the dead weight of a given bomb load, so as to take advantage of maximum load capacity in a bomber airplane and maximum travel distance to fuel ratio in a self-propelled type of bomb structure such as a guided missile. By the present invention, the preliminary forming by dishing of the heavy steel blanks is satisfactorily accomplished.

It is accordingly an important object of the present invention to provide an improved means for preparing a flat slab blank of steel for working into shell form.

Another object of the invention is to provide improvements in the dishing of the metal blanks.

A further object of the invention is to provide improved apparatus for preparing a thick metal blank for drawing into shell form.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying drawing, in

which:

The single FIGURE shows a fragmentary vertical sectional detail view through a trimming and dishing die apparatus with a steel blank disclosed therein in the form it takes after it has been dished.

For a 500 lb. bomb, the warhead shell will be about 250 lbs. in weight and the cupped blank, before drawing will have a wall thickness of from to 1 inch. For a 1,000 lb. bomb size the cup wall thickness is from 1 /2 to 1% inches and the weight approximately 500 lbs. To attain a cup of proper size from a flat slab blank, 21 diameter of to inches is provided, while for the 1,000 lb. bomb size, a blank of from to inches is provided.

In order to accommodate a fairly large range of mill variables in the working characteristics of steel slab, preliminary dishing, and thereafter cupping with an inter- 3,024,832 Patented Mar. 13, 1952 ice mediate annealing may be desirable. Accordingly, as the first step, a steel slab 15 may be dished cold in dishing die apparatus 17.

In the dishing die apparatus 17, trimming of the blank from a mill slab of polygonal outline is accomplished as well as dishing. To this end, the apparatus 17 includes a combination trimming and dishing punch 18 carried by a head plate 19' arranged to be secured .removably to a ram 20. Prior to a trimming and dishing stroke, the punch 18 is supported by the ram 20 above and in clearance relation to a trimming shear ring 21 supported by a base member 22 removably secured to an anvil member 23. For centering and stability against lateral displacement, the shear ring is seated within a complementary upwardly opening recess 24 in the top of the supporting member or block 22.

Prior to a trimming and dishing stroke of the punch 18, the polygonal blank or slab of steel is substantially centered upon the shear ring 21 over a circular central punch receiving opening 25 therein. At its upper inside corner, the shear ring 21 provides a shearing edge 27 which cooperates with a complementary lower outside circular shearing edge 28 on the lower nose end of the punch 13 so that as the punch is driven downwardly against the steel blank on the shear ring, scrap S is trimmed from the margin of the lank and remains upon the top of the shear ring 21 while the punch 18 moves on down through the punch clearance opening 25.

For uniformly bending the sheared blank 15 into dished form in the continuing stroke of the punch 18, a dishing cavity 29 is provided centrally within the punch 18 and opening downwardly to receive therein a complementary dishing dome 30 mounted within an upwardly opening recess 31 in the supporting block 22, the vertical wall of such recess being cylindrical and concentric with the shear ring recess 25 and of a diameter to receive the punch 18 freely the-rein. Means such as screws 32 may secure the dishing dome 3i) concentrically within the recess 31. For concentricity and to hold the dishing dome 30 against transverse displacement, it is provided with a central depending centering boss 32a fitting snugly within a complementary centering depression or counterbore 33 in the bottom of the recess 31.

At its upper end or crown the dishing dome 30 is, as shown, of generally rounded shape and is disposed in substantially the top plane of the shearing ring 21. Therefore, as the punch 18 drives down against the metal slab blank to trim the same, the pressure applied by the punch against the blank drives the blank tightly against the crown of the dishing dome 30. As the blank 15 bends down over the crown of the dome 30, an annular series of non-slip teeth, or serrations 34 on the crown of the dome bite into the material of the central portion of the blank and hold the blank against slipping or canting laterally as the dishing thereof progresses, with attendant pressures and stresses.

The stroke of the punch 18 continues until the blank 15 has been uniformly contracted and elongated into the dished form, resulting in a preferably rounded bottom and a flaring, in the present instance frusto-conical, side wall, with the bottom and side walls of the dish of uniform thickness and equal to the thickness of the original flat blank. At the end of the dishing stroke, the complementary surfaces of the dishing cavity 29 in the punch and on the dome cooperate to size the dished blank, that is to iron out any unequal or distorted portions of the dish and provide a uniform and symmetrical shape. This is of especial importance for cold working of the blank into the dished form.

In the final portion of the dishing stroke, the ring of scrap S lying upon the shearing ring 21 about the punch 18 3 is severed into a plurality of pieces by means such as depending knife edged scrap cutters or separators 35 secured to the head plate 19 about the base of the punch 18 and driving against the scrap toward the shear ring 21. There may be two or more of the cutters 35 as may be preferred.

In addition, near the end of the dishing stroke of the punch 18, a central aperture 37 is preferably punched in the base of the dished blank in order to facilitate sub sequent manipulations of the blank. Punching of the centering aperture 37 is accomplished herein by means of an aperturing punch 38 that projects down into the center of the dishing cavity 29 a limited distance to drive a slug L of material from the blank through a shearing aperture 39 in the crown of the dome 30. The punchedout slug drops down through a central bore 40 in the dishing dome 30 and is received in a clearance channel 41 in the bottom of the base block 22.

After completion of the dishing stroke of the punch 18, it is backed oil and in view of the downwardly opening and flaring form of the dishing cavity 29, the dished blank 15 clears from the cavity and remains upon the dome 3%. Assistance in clearing the dished blank 15 from within the recess 30 and the increased height of the recess as afforded by the central bore in the shearing ring 21, is afforded by an elevating stripper ring 42 normally resting within the bottom of the recess 31 about the base of the dishing dome 31) in normally clearance relation below the lower margin of the dishing punch 18 at the end of the dishing stroke. Means for elevating the stripper ring 42 may comprise reciprocal elevator rods 43 reciprocally guided through the anvil 23 and the base block 22.

It will be understood that modifications and variations may be effected Without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. In apparatus for trimming and dishing a heavy metal blank preparatory to drawing the blank, a circular stationary upwardly facing die assembly including a trimming shear ring, a base member supporting the shear ring and defining therewith a punch receiving recess, a dishing dome mounted within said recess and having a substantially rounded crown thereon within the plane of the top of said shear ring but so close to said plane that engagement of the crown by a metal blank carried by the shear ring is substantially coincident with shearing of the blank, said dishing dome having a forming surface flaring generally frusto-conically from merger with said rounded crown, and a dishing punch vertically reciprocably mounted relative to the shear ring and dishing dome and having a downwardly opening dishing cavity provided with a rounded base and flaring from said base generally frusto-conically substantially complementary to said rounded crown and frusto-conical forming surface of the dishing dome, said punch having a peripheral shearing edge coactive with the shear ring during a shearing and dishing stroke of the punch to shearingly trim a blank supported upon the shear ring over the punch receiving recess and over said dishing dome, the continuing dishing stroke of the punch after shearing acting to dish the trimmed blank over the dishing dome, said downwardly opening rounded base and generally frusto-conical form of the dishing cavity .of the dishing punch enabling selfclearing of the dished blank from the dishing cavity to remain on the dishing dome when the dishing punch is backed oif.

2. In apparatus for trimming and dishing a heavy metal blank preparatory to drawing the blank, a circular stationary upwardly facing die assembly including a trimming shear ring, a base member supporting the shear ring and defining therewith a punch receiving recess, a dishing dome mounted within said recess and having a substantially rounded crown thereon within the plane of the top of said shear ring but so close to said plane that engagement of the crown by a metal blank carried by the shear ring is substantially coincident with shearing of the blank, said dishing dome having a forming surface flaring generally frus-to-conically from merger with said rounded crown, a dishing punch vertically reciprocably mounted relative to the shear ring and dishing dome and having a downwardly opening dishing cavity provided with a rounded base and flaring from said base generally frustocomically substantially complementary to said rounded crown and frusto-conical forming surface of the dishing dome, said punch having a peripheral shearing edge 00- active with the shear ring during a shearing and dishing stroke of the punch to shearingly trim a blank supported upon the shear ring over the punch receiving recess and over said dishing dome, the continuing dishing stroke of the punch after shearing acting to dish the trimmed blank over the dishing dome, and a series of non-slip teeth on the rounded crown of the dishing dome for biting into the material of the blank after the blank has been sheared and is pressed onto the crown of the dishing dome incident to dishing pressure by the punch whereby to hold the blank against slipping or canting laterally as the dishing progresses, said downwardly opening rounded base and generally frusto-conical form of the dishing cavity of the dishing punch enabling self-clearing of the dished blank from the dishing cavity to remain on the dishing dome when the dishing punch is backed off.

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